Emergent psychopathology in Alzheimer's disease patients over 12 months associated with functional, not cognitive, changes

In a large, well-characterized population of community-dwelling persons with Alzheimer's disease (AD), we investigated the emergence of behavioral symptomatology and its association with changes in cognitive, global-clinical, and functional status. Behavioral Rating Scale for Dementia (BRSD) item responses from 235 AD patients with varying levels of dementia severity and without significant behavioral disturbance were taken from the baseline and 12-month visits in a study of cognitive and behavioral instruments. Item-level analysis revealed new symptoms at every dementia severity level. The symptoms that emerged in the greatest proportion of patients were change in weight, change in appetite, diurnal confusion, uncooperativeness, restlessness, clingy behavior, loss of initiative, and change in sleeping pattern. Changes in cognitive status over the 12 months were associated with changes in functional status and not with the emergence of behavioral symptomatology; however, change in the latter two domains tended to be associated. The findings support the hypothesis that increasing behavioral disturbance is not strongly associated with decreasing cognitive status and that, except for psychotic symptoms, a previously observed association between dementia severity and behavioral status may have been mediated partly by changes in functional abilities.